W. D. Hamilton

The second volume of his collected papers, Evolution of Sex, was published in 2002, and the third and final volume, Last Words, in 2005.

He returned to London from Africa on 29 January 2000. He was admitted to University College Hospital, London, on 30 January 2000. He was transferred to Middlesex Hospital on 5 February 2000 and died there on 7 March 2000. An inquest was held on 10 May 2000 at Westminster Coroner's Court to inquire into rumours about the cause of his death. The coroner concluded that his death was due to "multi-organ failure due to upper gastrointestinal haemorrhage due to a duodenal diverticulum and arterial bleed through a mucosal ulcer". Following reports attributing his death to complications arising from malaria, the BBC Editorial Complaints Unit's investigation established that he had contracted malaria during his final African expedition. However, the pathologist had suggested the possibility that the ulceration and consequent haemorrhage had resulted from a pill (which might have been taken because of malarial symptoms) lodging in the diverticulum; but, even if this suggestion were correct, the link between malaria and the observed causes of death would be entirely indirect.

A secular memorial service (he was an agnostic) was held at the chapel of New College, Oxford on 1 July 2000, organised by Richard Dawkins. He was buried near Wytham Woods. He, however, had written an essay on My intended burial and why in which he wrote:

His collected papers, entitled Narrow Roads of Gene Land, began to be published in 1996. The first volume was entitled Evolution of Social Behaviour.

Hamilton started to publish his collected papers in 1996, along the lines of Fisher's collected papers, with short essays giving each paper context. He died after the preparation of the second volume, so the essays for the third volume come from his coauthors.

During the 1990s, Hamilton became increasingly interested in the controversial argument that the origin of HIV lay in oral polio vaccines trials conducted by Hilary Koprowski in Africa during the 1950s. A letter by Hamilton on the topic to the major peer-reviewed journal Science was rejected in 1996. Despite this rejection, he gave supportive declarations on the hypothesis to the BBC and wrote the foreword of a 1999 book, The River, by journalist Edward Hooper, who investigated the hypothesis. To look for indirect evidence of the OPV hypothesis by assessing natural levels of simian immunodeficiency virus, in primates, in early 2000, Hamilton and two others ventured on a field trip to the then-war-torn Democratic Republic of the Congo. However, none of the over 60 urine and faecal samples collected by Hamilton contained detectable SIV virus.

Hamilton became known for his theoretical work expounding a rigorous genetic basis for the existence of altruism, an insight that was a key part of the development of the gene-centered view of evolution. He is considered one of the forerunners of sociobiology. Hamilton published important work on sex ratios and the evolution of sex. From 1984 to his death in 2000, he was a Royal Society Research Professor at Oxford University.

In 1980, he was elected a Fellow of the Royal Society, and in 1984, he was invited by Richard Southwood to be the Royal Society Research Professor in the Department of Zoology at Oxford, and a fellow of New College, where he remained until his death.

Hamilton was a visiting professor at Harvard University and later spent nine months with the Royal Society's and the Royal Geographical Society's Xavantina-Cachimbo Expedition as a visiting professor at the University of São Paulo. From 1978 Hamilton was Professor of Evolutionary Biology at the University of Michigan. Simultaneously, he was elected a Foreign Honorary Member of American Academy of Arts and Sciences. His arrival sparked protests and sit-ins from students who did not like his association with sociobiology. There he worked with the political scientist Robert Axelrod on the prisoner's dilemma, and was a member of the BACH group with original members Arthur Burks, Robert Axelrod, Michael Cohen, and John Holland.

Hamilton was regarded as a poor lecturer. This shortcoming would not affect the recognition of his work, however, as it was popularised by Richard Dawkins in the book The Selfish Gene published in 1976.

The paper introduced the concept of the "unbeatable strategy", which John Maynard Smith and George R. Price were to develop into the evolutionarily stable strategy (ESS), a concept in game theory not limited to evolutionary biology. Price had originally come to Hamilton after deriving the Price equation, and thus rederiving Hamilton's rule. Maynard Smith later peer reviewed one of Price's papers, and drew inspiration from it. The paper was not published but Maynard Smith offered to make Price a co-author of his ESS paper, which helped to improve relations between the men. Price committed suicide in 1975, and Hamilton and Maynard Smith were among the few present at the funeral.

In his 1970 paper Selfish and Spiteful Behaviour in an Evolutionary Model Hamilton considers the question of whether harm inflicted upon an organism must inevitably be a byproduct of adaptations for survival. What of possible cases where an organism is deliberately harming others without apparent benefit to the self? Such behaviour Hamilton calls spiteful. It can be explained as the increase in the chance of an organism's genetic alleles to be passed to the next generations by harming those that are less closely related than relationship by chance.

In 1966, he married Christine Friess; the couple had three daughters, Helen, Ruth and Rowena. 26 years later they amicably separated. From 1994, Hamilton found companionship with Maria Luisa Bozzi, an Italian science journalist and author.

where C is the cost in fitness to the actor, r the genetic relatedness between the actor and the recipient, and B is the fitness benefit to the recipient. Fitness costs and benefits are measured in fecundity. r is a number between 0 and 1. His two 1964 papers entitled The Genetical Evolution of Social Behaviour are now widely referenced.

Between 1964 and 1977, Hamilton was a lecturer at Imperial College London. Whilst there he published a paper in Science on "extraordinary sex ratios". Fisher (1930) had proposed a model as to why "ordinary" sex ratios were nearly always 1:1 (but see Edwards 1998), and likewise extraordinary sex ratios, particularly in wasps, needed explanations. Hamilton had been introduced to the idea and formulated its solution in 1960 when he had been assigned to help Fisher's pupil A.W.F. Edwards test the Fisherian sex ratio hypothesis. Hamilton combined his extensive knowledge of natural history with deep insight into the problem, opening up a whole new area of research.

The field of social evolution, of which Hamilton's Rule has central importance, is broadly defined as being the study of the evolution of social behaviours, i.e. those that impact on the fitness of individuals other than the actor. Social behaviours can be categorized according to the fitness consequences they entail for the actor and recipient. A behaviour that increases the direct fitness of the actor is mutually beneficial if the recipient also benefits, and selfish if the recipient suffers a loss. A behaviour that reduces the fitness of the actor is altruistic if the recipient benefits, and spiteful if the recipient suffers a loss. This classification was first proposed by Hamilton in 1964.

William Donald Hamilton FRS (1 August 1936 – 7 March 2000) was a British evolutionary biologist, recognised as one of the most significant evolutionary theorists of the 20th century.

Hamilton was born in 1936 in Cairo, Egypt, the second of seven children. His parents were from New Zealand; his father A.M. Hamilton was an engineer, and his mother B.M. Hamilton was a physician. The Hamilton family settled in Kent. During the Second World War, Hamilton was evacuated to Edinburgh. He became interested in natural history at an early age and spent his spare time collecting butterflies and other insects. In 1946, he discovered E.B. Ford's New Naturalist book Butterflies, which introduced him to the principles of evolution by natural selection, genetics, and population genetics.